题目 我的代码

#include<bits/stdc++.h>
using namespace std;
int a,b,c,d;
int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);cout.tie(0);
    cin>>a>>b>>c>>d; 
    int m=__gcd(b,d);
	a*=d/m;
    c*=b/m;
    a+=c;
    b*=d/m;
    m=__gcd(a,b);
    a/=m;
    b/=m;
       cout<<a<<' '<<b;
    return 0;
}

40分求助

第二题 我的代码

#include<bits/stdc++.h>
using namespace std;
int mumb(int t) {
    int base = 1;
    int dd = 1;

    while (t > 9 * base * dd) {
        t -= 9 * base * dd;
        base *= 10;
        dd++;
    }

    int number = base + (t - 1) / dd;
    int dx = (t - 1) % dd;
    stringstream ss;
    ss << number;
    string numberString = ss.str();
    return numberString[dx] - '0';
}


vector<long long> e(int n) {
    vector<long long> p(n + 1, 0);

    for (int i = 1; i <= n; i++) {
        p[i] = p[i - 1] + mumb(i);
    }

    return p;
}

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);cout.tie(0);
    int n, q;
    cin >> n >> q;

    vector<long long> p = e(n);

    for (int i = 0; i < q; i++) {
        int type;
        cin >> type;

        if (type == 1) {
            int x;
            cin >> x;
            cout << mumb(x) << " ";
        } else if (type == 2) {
            int x, y;
            cin >> x >> y;
            cout << p[y] - p[x - 1] << " ";
        }
    }

    return 0;
}

第三题

#include<bits/stdc++.h>
using namespace std;
int maximumSum(int n, int m, int k, const vector<int>& nums) 
{
    vector<int> dp(n+1, 0);
    dp[1] = nums[0];

    for (int i = 2; i <= n; i++) {
        dp[i] = max(dp[i-k] + nums[i-1], dp[i-1]);
    }

    return dp[n];
}

int main() 
{
	ios::sync_with_stdio(0);
	cin.tie(0);cout.tie(0);
    int n, m, k;
    cin >> n >> m >> k;

    vector<int> nums(n);
    for (int i = 0; i < n; i++) {
        cin >> nums[i];
    }

	int rp;
	rp++;
    int ans = maximumSum(n, m, k, nums);
    cout << ans << endl;

    return 0;
}

求求dalao帮忙 谢谢了 急需